The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Strut-type suspension systems are well known in the motor vehicle industry. Such telescopic suspension systems are also commonly known as McPherson shock absorbers. A strut-type shock absorber assembly normally incorporates a hydraulic damper and is used as one of the locating members for the wheel of the motor vehicle. A strut-type shock absorber assembly typically includes a coil spring concentrically disposed around a shock absorber. The coil spring extends between an upper spring seat, which is a part of a top mount assembly for the strut-type shock absorber assembly, and a lower spring seat, which is attached to the shock absorber component of the strut-type shock absorber assembly.
The lower spring seat can be a single piece component made of metal or plastic. A plastic spring seat is lighter in weight than its metal counterpart, and for that reason is particular desirable with motor vehicle manufacturers for the reason that it reduces the weight of the overall assembly. An annular inner portion of the lower spring seat is designed to interface with an outer tube of the shock absorber. The lower spring seat supports and maintains the correct position of the coil spring under various driving conditions of the vehicle. The lower spring seat resists braking loads, wear, abrasion, changing loads and impacts by stones and other road debris.
During a severe impact, however, the coil spring may fail (i.e., fracture). For this reason the lower spring seat may incorporate some structure that acts as a “catcher” to catch the fractured spring and reduce the chance of the fractured spring contacting the wheel of the vehicle. As such, the construction of the lower spring seat is a highly important consideration in the design of a strut-type shock absorber assembly.
A significant challenge when designing a plastic or composite reinforced spring seat component, however, is the generally low toughness of spring seats made from plastics or composites, when compared to spring seat components made from common metals such as steel. Accordingly, improving the toughness of a spring seat member, and particularly the catcher, without tangibly increasing its weight or expense, has proven to be a significant challenge.